They are consistently described as "tall, beautiful (if frightening), [and] covered in golden scales."
Alduin's wall has the Dragonguard's history represented on it, which was originally made up of Akaviri people. Are these Akaviri depicted the same men that were supposedly eaten by the Tsaesci, or are they the Tsaesci?
The Akaviri general's ghost, and the ancient Akaviri armor, are also regularly humanoid shaped. The only reason I wouldn't think these are Akavir men from Atmora is they are said to have been "eaten long ago," suggesting they may have never gained any kind of power to be able to travel to Tamriel as they are depicted in those events.
And of course there is the Akaviri Potentate, but we have never gotten a clear description of him other than the usual, which may be propoganda.
Sources tend to vary.
Do you think the snake like appearance is propoganda or true? Is it an exaggeration of more minimal features? Do they have many breeds (like the Khajiit or Argonians) with different physiologies? Does anyone know any better sources?